DevOps: VPC Module: Update NAT Gateway EIP configuration and add addi…

[rxnjitth]

Issue ID : #22

Summary
Added essential outputs to the VPC module for improved reusability and integration.

Changes

• Added vpc_name output for the VPC resource name.
• Added internet_gateway_id output for the IGW ID.
• Added public_route_table_ids and private_route_table_ids outputs (lists for multi-AZ support).
• Added public_subnet_cidrs and private_subnet_cidrs outputs (lists of CIDR blocks).
• Added nat_gateway_elastic_ips output (list of EIP allocations for NAT GWs).

All new outputs are derived from existing resources, ensuring no breaking changes to current consumers.
Why?
The module previously only exposed basic IDs, limiting visibility and ease of use in multi-module setups (e.g., passing route tables to security groups or CIDRs to EC2 modules). This enhances production flexibility across environments without disrupting existing workflows.

Testing

• Verified outputs in a local Terraform plan/apply against a test AWS account.
• Confirmed backward compatibility—no diffs in existing output values.